Demographic Transition Reverses: Are the Wealthy Having More Kids?

University of Pennsylvania researcher Mikko Myrskyla and colleagues report in a new study in Nature that fertility rates are now rising in richer countries after falling for decades. According to the abstract:

During the twentieth century, the global population has gone through unprecedented increases in economic and social development that coincided with substantial declines in human fertility and population growth rates. The negative association of fertility with economic and social development has therefore become one of the most solidly established and generally accepted empirical regularities in the social sciences. As a result of this close connection between development and fertility decline, more than half of the global population now lives in regions with below-replacement fertility (less than 2.1 children per woman). In many highly developed countries, the trend towards low fertility has also been deemed irreversible. Rapid population ageing, and in some cases the prospect of significant population decline, have therefore become a central socioeconomic concern and policy challenge.

Here we show, using new cross-sectional and longitudinal analyses of the total fertility rate and the human development index (HDI), a fundamental change in the well-established negative relationship between fertility and development as the global population entered the twenty-first century. Although development continues to promote fertility decline at low and medium HDI levels, our analyses show that at advanced HDI levels, further development can reverse the declining trend in fertility. The previously negative development–fertility relationship has become J-shaped, with the HDI being positively associated with fertility among highly developed countries. This reversal of fertility decline as a result of continued economic and social development has the potential to slow the rates of population ageing, thereby ameliorating the social and economic problems that have been associated with the emergence and persistence of very low fertility.

Fascinating. So why might this reversal in fertility trends be happening? The Economist speculates: 

There are lots of social explanations of why fertility rates fall as countries become richer. The increasing ability of women in the developed world to control their own reproductive output is one, as is the related phenomenon of women entering the workplace in large numbers. The increasing cost of raising children in a society with more material abundance plays a part. So does the substitution of nationalised social-security systems for the support of offspring in old age. Falling rates of child mortality are also significant. Conversely, Dr Myrskyla speculates that the introduction of female-friendly employment policies in the most developed countries allows women to have the best of both worlds, and that this may contribute to the uptick.

No doubt all these social explanations are true as far as they go, but they do not address the deeper question of why people's psychology should have evolved in a way that makes them want fewer children when they can afford more. There is a possible biological explanation, though. This is that there are, broadly speaking, two ways of reproducing.

One way is to churn out offspring in large numbers, turn them out into an uncaring world, and hope that one or two of them make it. The other is to have but a few progeny and to dote on them, ensuring that they grow up with every possible advantage for the ensuing struggle with their peers for mates and resources. The former is characteristic of species that live in unstable environments and the latter of species whose circumstances are predictable.

Viewed in comparison with most animals, humans are at the predictable-environment and doting-parent end of the scale, but from a human perspective those in less developed countries are further from it than those in rich ones. One interpretation of the demographic transition, then, is that the abundance which accompanies development initially enhances the instinct to lavish care and attention on a few offspring. Only when the environment becomes super-propitious can parents afford more children without compromising those they already have—and only then, as Dr Myrskyla has now elucidated, does the birth-rate start to rise again.

Backing up this speculation is the fact that the highest fertility rates today are found in the least stable and least prosperous countries.

More than decade ago, I noticed and reported in Slate that wealthier Americans were having more kids. In my article "Kids as Status Symbols," I asked:

So, you've got the beach house compound on Nantucket, the 63-foot Hinckley sailboat, the corporate jet, the nanny, and the gardener; and your stay-at-home spouse with the advanced academic degree heads up the local United Way campaign. What other acquisition might serve your high economic and social status? How about having some more kids?

As I reported: 

I have noticed that many of my wealthier acquaintances, people who live in tonier suburbs like Potomac, Md., or Darien, Conn., are bucking the trend toward smaller families. Many have three or four kids. Some intriguing, if sketchy, data suggest that at the highest levels of wealth and income, the trend is toward larger, not smaller, families.

For example, Mendelsohn Research–a company that supplies consumer research to advertisers, advertising agencies, and publishing companies–offers some suggestive data. Mendelsohn's most recent annual survey shows that those households with children where the annual family income exceeds $250,000 are blessed with an average of 2.3 children currently at home. That is 0.5 kids more than the upper-middle-class average and the same number as the lowest census income category. And because the Mendelsohn data don't include kids who have left home–while the census data do–the number of children born in these very wealthy families could be even higher.

One other interesting figure comes from the very tiptop of the wealth scale. The households that compose the Forbes 400 richest Americans average 2.88 children. That's 1.08 kids more than the upper-middle class can afford.

These added kids provide many opportunities for status signaling. Wealthy parents can talk endlessly at the country club about the costs of Maine summer camps, high-school semesters abroad, little Andrew's sailing trophies, and what hunt Sarah rides with regularly. And of course, there are schools and universities. Did they prep at St. Albans or Choate? How well are they doing at Harvard, Yale, or Middlebury? Being able to provide lavishly for a large number of children shows that you've really got it made.

This is not to say that rich people don't love their kids. Rather, kids today are not only little bundles of joy but also are perhaps the ultimate symbols of worldly success and status. Perhaps we are now seeing a new social phenomenon–trophy kids.

Just a final side note: I was later told that then-Vice-President Al Gore was very interested in my Slate article and wanted to include the information in his speeches. His staff tried fact-checking it with the Mendelsohn folks, and the head of the company denied that he had supplied me with any information nor could he confirm it. Amusingly, the company president failed to check with his staff members who had very kindly run the numbers for the over-$250,000 income group specifically for me. 

For those you who just can't get enough on fertility trends, you might want to look at my recent column on "The Invisible Hand of Population Control."